1. Institut für Pharmazie, Abteilung für Pharmazeutische Chemie, Universität Hamburg, Bundesstrasse 45, D-20146 Hamburg, Germany, Developmental Therapeutics Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute, Rockville, Maryland 20852, Centre National de la Recherche Scientifique, Station Biologique, BP 74, F-29682 Roscoff, France, Department of Pharmaceutical Chemistry, University of Marburg, Marbacher Weg 6, D-35032 Marburg, Germany, and Department of Medicinal Chemistry,...